参考《Windows内核安全与驱动开发》的加密解密Minifilter
eg：
eg：
这个项目主要实现了一个简单的DLP(Data leakage prevention)，每当目标进程创建目标扩展名的文件，
且有写入倾向时，会对文件写入加密头，将数据加密，并标记。这样，保证数据在磁盘中是以密文的形式存放的。
以后尝试打开该文件的进程，会根据进程的权限（明文，密文，无权限），进行透明解密或者拒绝访问。
并且，可以通过C#的界面进行进程策略配置，以及对一个非空且未加密文件进行特权加密，
或者对一个已加密文件进行特权解密，这样可以将该文件排除或者纳入驱动控制的范围内。
Windows 10 x64
VMware Workstation Pro 16
Visual Studio 2019
Notepad.exe x64
FileSpy.exe x64
2021.04.16 项目立项
2021.05.05 实现了基于SwapBuffers的异或加密解密
2021.05.07 写入、识别加密文件头，对记事本隐藏加密文件头
2021.05.10 实现了应用端到驱动的简单通信
2021.05.12 实现了从客户端传入信任进程和扩展名匹配规则到驱动
2021.05.13 大更新，不再使用《Windows内核安全与驱动开发》对于ByteOffset和EndOfFile的处理方式
2021.05.15 使用微软Cryptography API: Next Generation（CNG）库的AES-128 ECB模式
2021.05.16 完善匹配规则，实现双向链表存储
2021.05.19 驱动中实现进程可执行文件的Hash验证（SHA-256）（注释掉了）
2021.05.20 解决BCryptEncrypt自动填充数据，但EOF没有改变，导致文件移动后，加密后的填充数据丢失
2021.08.29 解决链表中进程匹配问题，解决加密解密后EOF问题
2021.09.03 做了代码优化
2021.09.06 双向链表插入移除节点时用了自旋锁，StreamContext加了读写锁，保证多线程下数据的安全
2021.09.11 取消了全局变量CheckHash的使用，将其放入每个链表的节点中
2021.09.12 双向链表遍历时加了共享锁
2021.10.31 处理已存在的未加密文档（有bug未解决），将进程加密策略双向链表操作单独放在了LinkedList.c中，
2021.11.01 进程设置三种权限，增加特权解密功能，特权解密功能
2021.11.03 解决notepad的打开，另存为按钮蓝屏问题：EptIsTargetExtension函数没有拦截到无关操作；
------------增加特权解密命令首先判断是否存在加密头操作
2021.11.04 代码回滚，去掉了10.31号的处理已存在的未加密文档操作
2021.11.08 新增桌面和内核通信函数封装的dll
2021.11.09 新增C# WPF框架的界面，通过调用dll和内核通信
接下来将会考虑双缓冲方面的问题（shadow fileobject或者重定向到虚拟的卷）；
保护驱动：进程安全问题 防注入
对大文件的处理
多线程加解密的问题
桌面到内核数据包加密
密钥安全问题
文件大小记录问题（将StreamContext中的数据导出，或者用链表做同步后存入本地，或者写入加密头中）
1.复制粘贴已加密文件，有一定几率会先进入PreWrite，造成重复加密，导致数据损坏
2.暂不支持notepad++.exe wps.exe wpp.exe等，notepad++的读写方式和正常的不太一样，
3.已存在的未加密大文件，有写入倾向，重新添加加密头，读取源文件时会导致偏移出错，
这是因为大文件不是全部读入缓冲的，只是一部分源文件头+修改后的部分源文件头的格式
4.没有做特权加解密线程与minifilter线程之间的文件操作保护
因为书中是基于传统文件过滤驱动的，用在Minifilter中有很多的出入，因此参考了很多相关的资料，谢谢
https://github.com/microsoft/Windows-driver-samples/tree/master/filesys/miniFilter/swapBuffers
https://github.com/microsoft/Windows-classic-samples
https://github.com/minglinchen/WinKernelDev/tree/master/crypt_file
https://github.com/SchineCompton/Antinvader
https://github.com/shines77/Antinvader2015
https://github.com/comor86/MyMiniEncrypt
https://github.com/guidoreina/minivers
https://github.com/xiao70/X70FSD
https://github.com/dokan-dev/dokany
《Windows内核安全与驱动开发》
《Windows NT File System Internals》
何明 基于Minifilter微框架的文件加解密系统的设计与实现 2014 年 6 月
刘晗 基于双缓冲过滤驱动的透明加密系统研究与实现 2010 年 4 月
何翔 基于 IBE 和 FUSE 的双向透明文件加密系统的研究与实现 2017 年 4 月
//首先需要把项目属性Drivers Settings->Target Platform改成Desktop
//关于缓冲方面的问题，加上IRP_MJ_CLEANUP，在PreCleanUp中清一下缓存，EptFileCacheClear(FltObjects->FileObject);
//在PreRead和PreWrite中过滤掉以下两步
if (!FlagOn(Data->Iopb->IrpFlags, (IRP_PAGING_IO | IRP_SYNCHRONOUS_PAGING_IO | IRP_NOCACHE)))
return FLT_PREOP_SUCCESS_NO_CALLBACK;
//判断是否为目标扩展名，进一步筛选，减少后续操作
if (!EptIsTargetExtension(Data))
return FLT_PREOP_SUCCESS_NO_CALLBACK;
//然后注意，PostRead中，是在RtlCopyMemory之前解密；PreWrite中，是在RtlCopyMemory之后加密
//但是PreWrite中，iopb->Parameters.Write.Length的大小是0x1000，和真正数据长度是不符的，
//可以使用FltQueryInformationFile查询EOF获得文件的真正大小
//这样基本上就可以了。
//写入加密文件头"ENCRYPTION"大小PAGE_SIZE
//这里不需要用FltSetInformationFile分配EOF大小
//初始化事件（重要）
KeInitializeEvent(&Event, SynchronizationEvent, FALSE);
//写入加密标记头
ByteOffset.QuadPart = 0;
Status = FltWriteFile(FltObjects->Instance, FltObjects->FileObject, &ByteOffset, Length, Buffer,
FLTFL_IO_OPERATION_NON_CACHED | FLTFL_IO_OPERATION_DO_NOT_UPDATE_BYTE_OFFSET, NULL, EptReadWriteCallbackRoutine, &Event);
//等待FltWriteFile完成
KeWaitForSingleObject(&Event, Executive, KernelMode, TRUE, 0);
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//读取加密文件头
//将文件读入缓冲区
Length = FILE_FLAG_SIZE;（重要）
KeInitializeEvent(&Event, SynchronizationEvent, FALSE);
ByteOffset.QuadPart = 0;
Status = FltReadFile(FltObjects->Instance, FltObjects->FileObject, &ByteOffset, Length, ReadBuffer,
FLTFL_IO_OPERATION_NON_CACHED | FLTFL_IO_OPERATION_DO_NOT_UPDATE_BYTE_OFFSET, NULL, EptReadWriteCallbackRoutine, &Event);
KeWaitForSingleObject(&Event, Executive, KernelMode, TRUE, 0);
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//对记事本隐藏文件头
//Read和Write同理，这里只展示Read
//PreRead:
//忽略以下操作（重要）
if (FlagOn(Data->Flags, FLTFL_CALLBACK_DATA_FAST_IO_OPERATION))
{
return FLT_PREOP_DISALLOW_FASTIO;
}
if (Data->Iopb->Parameters.Read.Length == 0)
{
return FLT_PREOP_SUCCESS_NO_CALLBACK;
}
if (!FlagOn(Data->Iopb->IrpFlags, (IRP_PAGING_IO | IRP_SYNCHRONOUS_PAGING_IO | IRP_NOCACHE)))
{
return FLT_PREOP_SUCCESS_NO_CALLBACK;
}
//设置偏移加FILE_FLAG_SIZE，Write不需要修改偏移（重要）
Data->Iopb->Parameters.Read.ByteOffset.QuadPart += FILE_FLAG_SIZE;
FltSetCallbackDataDirty(Data);
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//第三步，这里我们把以上两部分组合在一起，实现一个最小化的基本功能的加密解密系统
//这里需要添加的是IRP_MJ_QUERY_INFORMATION
//因为之前加上了PAGE_SIZE大小的文件加密头；所以需要在PostQueryInformation中EOF减掉PAGE_SIZE,
//否则记事本每次保存都会在数据之后加上PAGE_SIZE的空白
//这一步按照《Windows内核安全与驱动开发》就可以了
//使用了如下结构体作为数据头
typedef struct EPT_MESSAGE_HEADER
{
int Command;
int Length;
}EPT_MESSAGE_HEADER, * PEPT_MESSAGE_HEADER;
//使用结构体
//扩展名用 , （英文）分隔，用 , （英文）结束 例如：txt,docx，并在count中记录数量
typedef struct EPT_PROCESS_RULES
{
char TargetProcessName[260];
char TargetExtension[100];
int count;
}EPT_PROCESS_RULES, * PEPT_PROCESS_RULES;
//客户端发送进程规则
memset(Buffer, 0, MESSAGE_SIZE);
MessageHeader.Command = 2;
MessageHeader.Length = MESSAGE_SIZE - sizeof(MessageHeader);
RtlMoveMemory(Buffer, &MessageHeader, sizeof(MessageHeader));
RtlMoveMemory(ProcessRules.TargetProcessName, "notepad.exe", sizeof("notepad.exe"));
RtlMoveMemory(ProcessRules.TargetExtension, "txt,", sizeof("txt,"));
ProcessRules.count = 1;
RtlMoveMemory(Buffer + sizeof(MessageHeader), &ProcessRules, sizeof(EPT_PROCESS_RULES));
if (!EptUserSendMessage(Buffer))
{
printf("EptUserSendMessage failed.\n");
return 0;
}
//在驱动MessageNotifyCallback函数中接收
RtlMoveMemory(&ProcessRules, Buffer + sizeof(EPT_MESSAGE_HEADER), sizeof(EPT_PROCESS_RULES));
//将扩展名分隔开，并比较
for (int i = 0; i < ProcessRules.count; i++)
{
memset(TempExtension, 0, sizeof(TempExtension));
count = 0;
while (strncmp(lpExtension, ",", 1))
{
TempExtension[count++] = *lpExtension;
//DbgPrint("lpExtension = %s.\n", lpExtension);
lpExtension++;
}
RtlInitAnsiString(&AnsiTempExtension, TempExtension);
AnsiTempExtension.MaximumLength = sizeof(TempExtension);
if (NT_SUCCESS(RtlAnsiStringToUnicodeString(&Extension, &AnsiTempExtension, TRUE)))
{
if (RtlEqualUnicodeString(&FileNameInfo->Extension, &Extension, TRUE))
{
FltReleaseFileNameInformation(FileNameInfo);
RtlFreeUnicodeString(&Extension);
//DbgPrint("EptIsTargetExtension hit.\n");
return TRUE;
}
RtlFreeUnicodeString(&Extension);
}
//跳过逗号
lpExtension++;
}
https://www.microsoft.com/en-us/download/details.aspx?id=30688
//需要在微软官网下载Cryptographic Provider Development Kit，
//项目->属性的VC++目录的包含目录，库目录设置相应的位置
//链接器的常规->附加库目录C:\Windows Kits\10\Cryptographic Provider Development Kit\Lib\x64
//输入->附加依赖项一定要设置为ksecdd.lib
//按照微软的sample修改，https://docs.microsoft.com/en-us/windows/win32/seccng/encrypting-data-with-cng
//在DriverEntry中初始化加密的Key，存入全局变量AES_INIT_VARIABLES AesInitVar中，
//在EncryptUnload中CleanUp相关的Key和分配的内存
typedef struct AES_INIT_VARIABLES
{
BCRYPT_ALG_HANDLE hAesAlg;
BCRYPT_KEY_HANDLE hKey;
PUCHAR pbKeyObject;
BOOLEAN Flag;
}AES_INIT_VARIABLES, * PAES_INIT_VARIABLES;
//因为每次Data->Iopb->Parameters.Write.Length和Data->Iopb->Parameters.Read.Length都是PAGE_SIZE的整数倍
//又因为加密之后的数据比原始数据大，所以在PostRead中不需要调用BCryptDecrypt获取解密后数据大小
//但是PreWrite需要调用BCryptEncrypt返回加密后数据的大小，根据这个大小分配之后替换的内存，
//之后再调用BCryptEncrypt加密数据
if (ReturnLengthFlag)
{
//BCRYPT_BLOCK_PADDING
//Allows the encryption algorithm to pad the data to the next block size.
//If this flag is not specified, the size of the plaintext specified in the cbInput parameter
//must be a multiple of the algorithm's block size.
Status = BCryptEncrypt(AesInitVar.hKey, TempBuffer, OrigLength, NULL, NULL, 0, NULL, 0, LengthReturned, 0)
if (!NT_SUCCESS(Status))
{
DbgPrint("EptAesEncrypt BCryptEncrypt failed.\n");
ExFreePoolWithTag(TempBuffer, ENCRYPT_TEMP_BUFFER);
return FALSE;
}
DbgPrint("PreWrite AesEncrypt Length = %d LengthReturned = %d.\n", Length, *LengthReturned);
ExFreePoolWithTag(TempBuffer, ENCRYPT_TEMP_BUFFER);
return TRUE;
}
Status = BCryptEncrypt(AesInitVar.hKey, TempBuffer, OrigLength, NULL, NULL, 0, Buffer, *LengthReturned, LengthReturned, 0)
if (!NT_SUCCESS(Status))
{
DbgPrint("EptAesEncrypt BCryptEncrypt failed Status = %X.\n", Status);
ExFreePoolWithTag(TempBuffer, ENCRYPT_TEMP_BUFFER);
return FALSE;
}
//使用以下结构体
typedef struct EPT_PROCESS_RULES
{
LIST_ENTRY ListEntry;
char TargetProcessName[260];
char TargetExtension[100];
int count;
}EPT_PROCESS_RULES, * PEPT_PROCESS_RULES;
//在DriverEntry中InitializeListHead(&ListHead);，在Unload中EptListCleanUp();，释放所有内存
VOID EptListCleanUp()
{
PEPT_PROCESS_RULES ProcessRules;
PLIST_ENTRY pListEntry;
while (!IsListEmpty(&ListHead))
{
pListEntry = ExInterlockedRemoveHeadList(&ListHead, &List_Spin_Lock);
ProcessRules = CONTAINING_RECORD(pListEntry, EPT_PROCESS_RULES, ListEntry);
DbgPrint("Remove list node TargetProcessName = %s", ProcessRules->TargetProcessName);
ExFreePool(ProcessRules);
}
}
//在驱动MessageNotifyCallback函数中接收并插入链表
PEPT_PROCESS_RULES ProcessRules;
ProcessRules = ExAllocatePoolWithTag(PagedPool, sizeof(EPT_PROCESS_RULES), PROCESS_RULES_BUFFER_TAG);
if (!ProcessRules)
{
DbgPrint("DriverEntry ExAllocatePoolWithTag ProcessRules failed.\n");
return 0;
}
RtlZeroMemory(ProcessRules, sizeof(EPT_PROCESS_RULES));
RtlMoveMemory(ProcessRules->TargetProcessName, Buffer + sizeof(EPT_MESSAGE_HEADER), sizeof(EPT_PROCESS_RULES) - sizeof(LIST_ENTRY));
ExInterlockedInsertTailList(&ListHead, &ProcessRules->ListEntry, &List_Spin_Lock);
break;
//使用以下方式遍历比较进程名和扩展名
PEPT_PROCESS_RULES ProcessRules;
PLIST_ENTRY pListEntry = ListHead.Flink;
while (pListEntry != &ListHead)
{
ProcessRules = CONTAINING_RECORD(pListEntry, EPT_PROCESS_RULES, ListEntry);
//比较操作
pListEntry = pListEntry->Flink;
}
//这里用到了Windows-classic-samples-master\Samples\Security\SignHashAndVerifySignature
//中的ComputeHash函数计算Hash
NTSTATUS ComputeHash(
PUCHAR Data,
ULONG DataLength,
PUCHAR* DataDigestPointer,
ULONG* DataDigestLengthPointer)
//把exe文件读到Buffer
NTSTATUS EptReadProcessFile(
UNICODE_STRING ProcessName,
PUCHAR* Buffer,
PULONG Length
)
{
OBJECT_ATTRIBUTES ObjectAttributes;
NTSTATUS Status;
HANDLE FileHandle;
IO_STATUS_BLOCK IoStatusBlock;
FILE_STANDARD_INFORMATION FileStandInfo;
LARGE_INTEGER ByteOffset;
InitializeObjectAttributes(
&ObjectAttributes,
&ProcessName,
OBJ_CASE_INSENSITIVE,
NULL,
NULL);
Status = ZwOpenFile(
&FileHandle,
GENERIC_READ,
&ObjectAttributes,
&IoStatusBlock,
FILE_SHARE_VALID_FLAGS,
FILE_NON_DIRECTORY_FILE);
if (!NT_SUCCESS(Status))
{
//STATUS_SHARING_VIOLATION
DbgPrint("EptReadProcessFile ZwOpenFile failed Status = %X.\n", Status);
return Status;
}
//查询文件大小，分配内存
Status = ZwQueryInformationFile(
FileHandle,
&IoStatusBlock,
&FileStandInfo,
sizeof(FILE_STANDARD_INFORMATION),
FileStandardInformation);
if (!NT_SUCCESS(Status))
{
DbgPrint("EptReadProcessFile ZwQueryInformationFile failed.\n");
ZwClose(FileHandle);
return Status;
}
(*Buffer) = ExAllocatePoolWithTag(
PagedPool,
FileStandInfo.EndOfFile.QuadPart,
PROCESS_FILE_BUFFER_TAG);
if (!(*Buffer))
{
DbgPrint("EptReadProcessFile ExAllocatePoolWithTag Buffer failed.\n");
ZwClose(FileHandle);
return Status;
}
ByteOffset.QuadPart = 0;
Status = ZwReadFile(
FileHandle,
NULL, NULL, NULL,
&IoStatusBlock,
(*Buffer),
(ULONG)FileStandInfo.EndOfFile.QuadPart,
&ByteOffset,
NULL);
if (!NT_SUCCESS(Status))
{
DbgPrint("EptReadProcessFile ZwReadFile failed.\n");
ZwClose(FileHandle);
ExFreePool((*Buffer));
return Status;
}
*Length = (ULONG)FileStandInfo.EndOfFile.QuadPart;
return Status;
}
//在EptIsTargetProcess函数中判断Hash，CheckHash标志位是全局变量，在PreCreate中时，设为TRUE
if(CheckHash)
{
PUCHAR ReadBuffer = NULL;
ULONG Length;
Status = EptReadProcessFile(*ProcessName, &ReadBuffer, &Length);
if (NT_SUCCESS(Status))
{
if (EptVerifyHash(ReadBuffer, Length, ProcessRules->Hash))
{
if (ReadBuffer)
ExFreePool(ReadBuffer);
CheckHash = FALSE;
return TRUE;
}
else
{
if (ReadBuffer)
ExFreePool(ReadBuffer);
CheckHash = FALSE;
return FALSE;
}
}
return FALSE;
}
//这里在从客户端传入Hash到驱动之前，对Hash进行转换
//因为ULONGLONG是小端序，
//而ComputeHash输出的是十六进制的Hash值，是大端序
//做一下转换
ULONGLONG Hash[4];
Hash[0] = 0xa28438e1388f272a;
Hash[1] = 0x52559536d99d65ba;
Hash[2] = 0x15b1a8288be1200e;
Hash[3] = 0x249851fdf7ee6c7e;
ULONGLONG TempHash;
RtlZeroMemory(ProcessRules->Hash, sizeof(ProcessRules->Hash));
for (ULONG i = 0; i < 4; i++)
{
TempHash = Hash[i];
for (ULONG j = 0; j < 8; j++)
{
ProcessRules->Hash[8 * (i + 1) - 1 - j] = TempHash % 256;
TempHash = TempHash / 256;
}
}
//在PreSetInformation中（这里相当于给txt文件分配内存），将EOF对齐AES_BLOCK_SIZE，并在streamcontext中记录文件原始大小 因为分配内存时，直接分配了16的倍数，所以加解密时不需要再对齐了
case FileEndOfFileInformation:
{
PFILE_END_OF_FILE_INFORMATION Info = (PFILE_END_OF_FILE_INFORMATION)InfoBuffer;
if (Info->EndOfFile.QuadPart % AES_BLOCK_SIZE != 0)
{
StreamContext->FileSize = Info->EndOfFile.QuadPart - FILE_FLAG_SIZE;
Info->EndOfFile.QuadPart = (Info->EndOfFile.QuadPart / AES_BLOCK_SIZE + 1) * AES_BLOCK_SIZE;
}
else
{
StreamContext->FileSize = Info->EndOfFile.QuadPart - FILE_FLAG_SIZE;
}
DbgPrint("EncryptPreSetInformation FileEndOfFileInformation EndOfFile = %d.\n", Info->EndOfFile.QuadPart);
break;
}
case FileAllocationInformation:
{
PFILE_END_OF_FILE_INFORMATION Info = (PFILE_END_OF_FILE_INFORMATION)InfoBuffer;
if (Info->EndOfFile.QuadPart % AES_BLOCK_SIZE != 0)
{
StreamContext->FileSize = Info->EndOfFile.QuadPart - FILE_FLAG_SIZE;
Info->EndOfFile.QuadPart = (Info->EndOfFile.QuadPart / AES_BLOCK_SIZE + 1) * AES_BLOCK_SIZE;
}
else
{
StreamContext->FileSize = Info->EndOfFile.QuadPart - FILE_FLAG_SIZE;
}
DbgPrint("EncryptPreSetInformation FileAllocationInformation EndOfFile = %d.\n", Info->EndOfFile.QuadPart);
break;
}
//在EncryptPostQueryInformation中（这里是Read之前，记事本查询所需信息）， 调整EOF，因为加密解密时使16字节对齐的，解密后，会有16-原始大小的空白字符，需要调整EOF，
if (StreamContext->FileSize > 0 &&(StreamContext->FileSize % AES_BLOCK_SIZE != 0))
{
FileOffset = (StreamContext->FileSize / AES_BLOCK_SIZE + 1) * AES_BLOCK_SIZE - StreamContext->FileSize;
}
else if (StreamContext->FileSize > 0 && (StreamContext->FileSize % AES_BLOCK_SIZE == 0))
{
FileOffset = 0;
}
case FileStandardInformation:
{
PFILE_STANDARD_INFORMATION Info = (PFILE_STANDARD_INFORMATION)InfoBuffer;
Info->AllocationSize.QuadPart -= FILE_FLAG_SIZE;
Info->EndOfFile.QuadPart = Info->EndOfFile.QuadPart - FILE_FLAG_SIZE - FileOffset;
break;
}
对于已经被写过，但是没有加密头的文档，我选择的处理方式是：在PostCreate中记录相关的文件大小，文件名等
在PreClose中把文档全部读入缓冲区，加密，加上加密头，重新写回文件。
这里有点问题，读入的文档有一部分是重复的，所以我直接用偏移略过去了，另外修改了StreamContext中记录的
文件大小,以便于PostQueryInformation中对EOF做相关的处理（这块是因为加密前后数据大小的变化而做的操作）
//对于已经被写过数据的文件，当有写入的倾向时，在PostCreate中记录文件相关数据，在PreClose中重新加入加密头
NTSTATUS EptAppendEncryptHeader(IN PCFLT_RELATED_OBJECTS FltObjects, IN OUT PEPT_STREAM_CONTEXT StreamContext)
{
NTSTATUS Status;
PFLT_VOLUME Volume;
FLT_VOLUME_PROPERTIES VolumeProps;
LARGE_INTEGER ByteOffset;
ULONG ReadLength, LengthReturned, WriteLength, ErrorLength;
HANDLE hFile = NULL;
PFILE_OBJECT FileObject = { 0 };
//这里因为是PreClose，文件已经关闭了，需要重新手动打开
Status = FileCreateForHeaderWriting(FltObjects->Instance, &StreamContext->FileName, &hFile);
if (!NT_SUCCESS(Status))
{
DbgPrint("EptAppendEncryptHeader->FileCreateForHeaderWriting failed. Status = %x\n", Status);
return Status;
}
Status = ObReferenceObjectByHandle(hFile, STANDARD_RIGHTS_ALL, *IoFileObjectType, KernelMode, (PVOID*)&FileObject, NULL);
//不知道为何，这里读出的数据 = 原始数据 + 原始数据 + 后写入的数据，所以用偏移把开头的原始数据去掉了
ErrorLength = EptGetFileSize(FltObjects);
//根据FltWriteFile， FltReadFile对于Length的要求，Length必须是扇区大小的整数倍
Status = FltGetVolumeFromInstance(FltObjects->Instance, &Volume);
if (!NT_SUCCESS(Status)) {
DbgPrint("EptAppendEncryptHeader->FltGetVolumeFromInstance failed. Status = %x\n", Status);
if (NULL != hFile)
{
FltClose(hFile);
hFile = NULL;
}
return Status;
}
Status = FltGetVolumeProperties(Volume, &VolumeProps, sizeof(VolumeProps), &ReadLength);
if (NULL != Volume)
{
FltObjectDereference(Volume);
Volume = NULL;
}
PCHAR ReadBuffer, TempEncryptBuffer;
ReadLength = ErrorLength - (LONG)StreamContext->FileSize;
ReadLength = ROUND_TO_SIZE(ReadLength, VolumeProps.SectorSize);
//为FltReadFile分配内存
ReadBuffer = FltAllocatePoolAlignedWithTag(FltObjects->Instance, PagedPool, ReadLength, 'itRB');
if (!ReadBuffer)
{
DbgPrint("EptAppendEncryptHeader->FltAllocatePoolAlignedWithTag ReadBuffer failed.\n");
if (NULL != hFile)
{
FltClose(hFile);
hFile = NULL;
}
return STATUS_UNSUCCESSFUL;
}
RtlZeroMemory(ReadBuffer, ReadLength);
//将文件读入缓冲区
ByteOffset.QuadPart = StreamContext->FileSize; //去掉原始数据
Status = FltReadFile(FltObjects->Instance, FileObject, &ByteOffset, (ULONG)ReadLength, (PVOID)ReadBuffer,
FLTFL_IO_OPERATION_DO_NOT_UPDATE_BYTE_OFFSET | FLTFL_IO_OPERATION_NON_CACHED, NULL, NULL, NULL);
if (!NT_SUCCESS(Status))
{
//STATUS_PENDING
DbgPrint("EptAppendEncryptHeader->Append FltReadFile failed. Status = %X.\n", Status);
if (NULL != ReadBuffer)
{
FltFreePoolAlignedWithTag(FltObjects->Instance, ReadBuffer, 'itRB');
ReadBuffer = NULL;
}
if (NULL != hFile)
{
FltClose(hFile);
hFile = NULL;
}
return Status;
}
//获得加密后数据的大小
if (!EptAesEncrypt(FltObjects, (PUCHAR)ReadBuffer, &LengthReturned, TRUE))
{
DbgPrint("EptAppendEncryptHeader->EptAesEncrypt get buffer encrypted size failed.\n");
return FALSE;
}
WriteLength = LengthReturned + FILE_FLAG_SIZE;
WriteLength = ROUND_TO_SIZE(WriteLength, VolumeProps.SectorSize);
TempEncryptBuffer = FltAllocatePoolAlignedWithTag(FltObjects->Instance, PagedPool, WriteLength, 'itRB');
if (!TempEncryptBuffer)
{
DbgPrint("EptAppendEncryptHeader->FltAllocatePoolAlignedWithTag TempEncryptBuffer failed.\n");
if (NULL != ReadBuffer)
{
FltFreePoolAlignedWithTag(FltObjects->Instance, ReadBuffer, 'itRB');
ReadBuffer = NULL;
}
if (NULL != hFile)
{
FltClose(hFile);
hFile = NULL;
}
return STATUS_UNSUCCESSFUL;
}
RtlZeroMemory(TempEncryptBuffer, WriteLength);
RtlMoveMemory(TempEncryptBuffer, FILE_FLAG, strlen(FILE_FLAG));
RtlMoveMemory(TempEncryptBuffer + FILE_FLAG_SIZE, ReadBuffer, ReadLength);
//加密整体的数据
WriteLength -= FILE_FLAG_SIZE;
if (!EptAesEncrypt(FltObjects, (PUCHAR)TempEncryptBuffer + FILE_FLAG_SIZE, &WriteLength, FALSE))
{
DbgPrint("EptAppendEncryptHeader->EptAesEncrypt encrypte buffer failed.\n");
}
//DbgPrint("EptAppendEncryptHeader->Encrypted content = %s.\n", TempEncryptBuffer + FILE_FLAG_SIZE);
//修改文件大小，这个会在PostQueryInfo中修改EOF
ExEnterCriticalRegionAndAcquireResourceExclusive(StreamContext->Resource);
StreamContext->FileSize = ErrorLength - (LONG)StreamContext->FileSize;
ExReleaseResourceAndLeaveCriticalRegion(StreamContext->Resource);
//为写入文件开辟大小
FILE_END_OF_FILE_INFORMATION EOF = { 0 };
EOF.EndOfFile.QuadPart = ErrorLength - (LONG)StreamContext->FileSize + FILE_FLAG_SIZE;
Status = FltSetInformationFile(FltObjects->Instance, FileObject, &EOF, sizeof(FILE_END_OF_FILE_INFORMATION), FileEndOfFileInformation);
//DbgPrint("filesize %d EOF %d\n", ErrorLength - (LONG)StreamContext->FileSize, EOF.EndOfFile.QuadPart);
//写入带加密标记头的数据
ByteOffset.QuadPart = 0;
Status = FltWriteFile(FltObjects->Instance, FileObject, &ByteOffset, (ULONG)WriteLength + FILE_FLAG_SIZE, TempEncryptBuffer,
FLTFL_IO_OPERATION_NON_CACHED | FLTFL_IO_OPERATION_DO_NOT_UPDATE_BYTE_OFFSET, NULL, NULL, NULL);
if (!NT_SUCCESS(Status)) {
DbgPrint("EptAppendEncryptHeader->Append FltWriteFile failed. Status = %x\n", Status);
if (NULL != ReadBuffer)
{
FltFreePoolAlignedWithTag(FltObjects->Instance, ReadBuffer, 'itRB');
ReadBuffer = NULL;
}
if (NULL != TempEncryptBuffer)
{
FltFreePoolAlignedWithTag(FltObjects->Instance, TempEncryptBuffer, 'itRB');
TempEncryptBuffer = NULL;
}
if (NULL != hFile)
{
FltClose(hFile);
hFile = NULL;
}
return Status;
}
if (NULL != ReadBuffer)
{
FltFreePoolAlignedWithTag(FltObjects->Instance, ReadBuffer, 'itRB');
ReadBuffer = NULL;
}
if (NULL != TempEncryptBuffer)
{
FltFreePoolAlignedWithTag(FltObjects->Instance, TempEncryptBuffer, 'itRB');
TempEncryptBuffer = NULL;
}
if (NULL != hFile)
{
FltClose(hFile);
hFile = NULL;
}
DbgPrint("EptAppendEncryptHeader->Append FltWriteFile success.\n");
return EPT_APPEND_ENCRYPT_HEADER;
}
这个命令是由客户端传入的，用于把加密的文件，去掉加密头，解密
所以我用事件做了内核线程和PrePost的同步，保证不会同时处理同一个文件（未完成）
因为是自己创的线程，需要自己找到FileObject和Instance，用FltCreateFile打开FileObject，
通过符号链接，找到卷的DOS名，然后找到卷的Instance。
然后读加密的数据，解密，调整EOF，重新写回文件，这里要把StreamContext的Flag去掉，因为已经是正常的文件
最后刷新缓存。主要的功能函数是FileFunc.c的EptRemoveEncryptHeaderAndDecrypt(PWCHAR FileName)
这样就可以完成一个闭环，首先一个加密文件，可以特权解密，然后有写入倾向时，会再写入加密头，加密数据。
特权加密与特权解密类似，就是对于空文件的处理上加了一步。
主要的功能函数是FileFunc.c的EptAppendEncryptHeaderAndEncryptEx(PWCHAR FileName)
以我现在对于缓冲的理解，还找不到一个合适的位置以及时机，去处理已存在的未加密文档，重新添加加密头，
不同于特权加解密，写入加密头的同时，notepad也正在写入数据，这两块数据的同步，这一块还不懂
而且关于在多线程下的文件操作保护，应该要去操作FCB中的锁，现在还不太懂这块
注意FilterGetMessage的用法，需要加FILTER_MESSAGE_HEADER头，另外注意不要和FltSendMessage造成死锁
还有，这个函数桌面端的返回值，我查不到......
不再在dll的DLL_PROCESS_ATTACH中初始化端口，换到C#中了
实现了特权加密，特权解密和配置进程策略的功能，对驱动的返回值进行判断
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